Virtually, any well which produces liquid hydrocarbons such as crude oil, also produces a residual amount of natural gas and water. In the normal production or drilling facility, low pressure gas, if present in a limited quantity, is discharged into the atmosphere rather than being flared, saved or otherwise used for commercial purposes.
In the instance of offshore producing facilities, this residual gas is dissipated into the air by way of one or more flare booms which extend outwardly from the offshore structure. A flare booms is normally furnished to each offshore platform such that vented gas is carried away from the platform by prevailing wind, rather than being blown back onto the structure. When the gas is at a relatively low pressure, it is merely vented rather than being flared.
The term vent gas as herein utilized refers to that portion of the gas which is raised from a producing operation, but is at an insufficient pressure and/or insufficient quantity to warrant being conserved.
Since this residual natural gas is combustible and normally combustion supporting, it can constitute a danger to the platform from a safety consideration as well as a health consideration for the workers.
Once the gas enters the atmosphere it will as a rule become sufficiently diluted to be safe from further ignition. Even so, the gaseous mixture formed at the vent boom discharge port can be readily ignited into an open flame by natural causes such as by a flash of lightening. Offshore platforms or structures are normally isolated in a body of water. It stands to reason that in the event of an electrical storm, the accompanying lightning could constitute a flame-triggering medium for the vented gaseous mixture.
As a practical matter, in the Gulf of Mexico it is not an uncommon event for the vented gas to be ignited by lightning during an electrical storm. To extinguish the resulting flame however, often constitutes a difficult and dangerous procedure due to the vent boom structure extending outwardly over the water, and the lack of a convenient mechanism for extinguishing the flame. Further, such booms are normally installed at an angle of about 30.degree. to horizontal such that the vent gas stream will be released in an upward direction.